TW200428057A - Photo module - Google Patents

Abstract

The photo module of this invention comprises: a submount 1 having 4 pieces of photo diode 12 and 2 guiding grooves on its photo element mounting surface 16, and a fiber optics fixing member 2 having 4 V-shaped grooves 21, 4 concaved lenses 22, and 2 guiding rails 20 on its fiber optics fixing surface 26, and 4 fiber optics fixed on said fiber optics fixing member 2. The submount 1 and the fiber optics fixing member 2 are positioned to be fixed by the engagement of said guiding grooves 10 and said guiding rails 20. Therefore, a photo module by passive alignment method is enabled to be produced in mass production scale at low cost.

Description

200428057 (1) Description of the invention: (1) Technical field to which the invention belongs The present invention relates to an optical module using optical fibers and optical semiconductor components as optical connections. (II) Prior technology In recent years, with the expansion of infrastructure construction of backbone circuits, the optical communications market has focused on the preparation of equipment for user circuits and equipment that connects user-side circuits and backbone circuits. Specifically, I look forward to the enhancement of metropolitan area networks, access systems, and local area networks (LANs) in schools or companies, as well as the increase in speed and capacity of servers or routers in network service providers. Wait. In particular, the optical connection of a LAN in a school or company, or a server or router in a network service provider is called very short reach (VSR), or interconnection. However, these optical connections are for short distances, so high-speed and large-capacity signal transmission is expected. On the other hand, in order to expect a low cost, although high speed is mentioned, expensive equipment is not suitable for equipment required for optical connection having a transmission speed of 10 Gbps, for example. Because of this expectation, optical modules that transmit optical signals side by side at a maximum speed of 2.5 Gbps have attracted attention. In this optical module, a plurality of optical signals can be transmitted side by side when positioning and connecting a ribbon optical fiber and an optical semiconductor element as an optical fiber array. However, when this positioning is performed by centering, a low-cost optical module cannot be realized. Therefore, there are proposals for optical modules that are positioned in a passive alignment (Japanese Patent Application Laid-Open No. 7-77634, Japanese Patent Application Laid-Open No. 7-195940). 200428057 Fig. 7 is a cross-sectional view showing an example of the configuration of an optical module positioned by a conventional passive alignment method (refer to the document "Institute of Electronic Information and Communication Technology Research Report, LQE99-130, pl-6"). The positioning of the optical fiber 92 and the optical semiconductor element 94 is performed by inserting and adhering the guide pin 95 of the fiber ferrule 91 to the guide pin insertion hole 96 of the substrate 93. Here, the optical fiber 92 inserts the pair of guide pins 95 into the positioned optical fiber insertion portion. The optical semiconductor element 94 uses the same mask process as the guide pin insertion hole 96, and uses the formed positioning mark as the guide portion, and Positioned and fixed on the substrate 93. In the conventional passive alignment optical module, the installation of any optical fiber is performed at an earlier stage in the entire assembly process of the optical module. For example, in the optical module shown in FIG. 7, when the substrate 93 is mounted on a circuit substrate as a sub-substrate, in order to reduce the height of the module, the substrate 93 is vertically stood against the circuit substrate. From now on. At this time, after the substrate 93 is fixed to the circuit substrate, it becomes difficult to mount the optical fiber ferrule 91 to the substrate 93. Here, the installation of the optical fiber sleeve 91 having the optical fiber 92 and the substrate 93 having the optical semiconductor element 94 is performed earlier than the process of fixing the substrate 93 to the circuit substrate. Therefore, in the case where the process of installing the optical fiber is performed at an earlier stage of the entire assembly of the optical module, there is a problem that it causes an obstacle to processing or automation in subsequent processes. For example, in the processes of die bonding, wire bonding, and the like of an optical semiconductor element or a substrate provided with the optical semiconductor element to a circuit substrate, a special device for installing an optical fiber must be considered. Then, these problems are the factors that hinder the mass production and cost reduction of optical modules. 200428057 The present invention was successfully developed in order to solve the above problems, and its purpose is to provide an optical module suitable for mass production and low cost. (3) Summary of the Invention In order to achieve the above-mentioned object, the optical module of the present invention is characterized by: (1) having an optical semiconductor element provided on a predetermined first surface, and a first semiconductor element formed on the first surface; The sub-substrate of the positioning portion (2) has a fixing groove formed on the second surface and positioning and fixing the optical fiber, and is provided with respect to the fixing groove, and is configured to fix the optical fiber and the corresponding optical semiconductor element fixed to the fixing groove. The light emitted from either side is guided to the other concave mirror and the optical fiber fixing member of the second positioning portion formed on the second surface, (3) the optical fiber fixed to the fixing groove; (4) the first positioning portion and the second positioning portion One of them is a guide rail, and the other is formed by a guide groove fitted to the guide rail. The sub-substrate and the optical fiber fixing member are positioned and fixed by the fitting of the first positioning portion and the second positioning portion. In the module, the first positioning portion of the sub-board is fitted with the second positioning portion of the optical fiber fixing member, so that the optical semiconductor element and the optical fiber are positioned. Therefore, the optical module can be positioned by passive alignment. In addition, since the guide rail and the guide groove are used as positioning portions, the optical semiconductor element and the optical fiber can be positioned with high accuracy. The second surface of the optical fiber fixing member that fixes the optical fiber is disposed so as to face the first surface of the sub-substrate on which the optical semiconductor element is disposed. Therefore, the process of positioning and fixing the optical fiber fixing member to which the optical fiber is fixed to the sub-substrate can be carried out later in the process of sub-substrate on a circuit substrate and performing a chip junction method, wire bonding, and the like. Therefore, there will be no obstacles to processing or automation in the process of laminating the sub-substrate on the circuit substrate, 7-200428057 method, wire bonding, etc., so that it can realize mass production and low-cost optical modules. In addition, since the first surface of the optical fiber sub-substrate is arranged in parallel, the module height can be reduced. Furthermore, a concave mirror is provided as an optical system for guiding light between the optical fiber and the optical semiconductor element. Therefore, light emitted from any one of the optical fiber and the optical semiconductor element is collected and guided to the other side, so that a high light combining ratio can be achieved. The optical module can include: a sub-substrate having N (N is an integer of 2 or more) optical semiconductor elements, N fixing grooves parallel to each other, and an optical fiber fixing member having N concave mirrors provided for the N fixing grooves, respectively. , And N optical fibers respectively fixed in N fixing grooves. In this case, a plurality of optical signals can be transmitted in parallel, so an optical module capable of transmitting at a higher speed and a larger capacity can be provided.

In addition, since the optical semiconductor device is made of the same material as the sub substrate and uses the same semiconductor process, it can be formed as a single piece with the first positioning portion. Alternatively, the sub-substrate has a positioning mark formed by the same mask process as the first positioning portion, and the optical semiconductor element can be positioned as a reference by positioning the sub-substrate. In these cases, the optical semiconductor element and the first positioning portion can obtain a sub-substrate for positioning each other with high accuracy. In addition, the optical fiber fixing member can be made by integrally molding resin. In this case, the fixing groove, the concave mirror, and the second positioning portion can obtain the optical fiber fixing member positioned with each other with high accuracy. In addition, the second positioning portion may be formed to be substantially parallel to the fixing groove. In this case, it is easy to form the second positioning portion and the fixing groove mutually. 8-200428057 In addition, the cross-sectional shape of the guide rail taken in a vertical plane toward the long side direction can be pushed. In this case, the fitting of the guide rail and the guide groove can be facilitated. Furthermore, the optical module is provided between the optical semiconductor element and the concave mirror, and the light emitted from one of the optical fiber and the optical semiconductor element is directed to the other side. Condensing lens. In this case, together with the light collected by the concave mirror, the light combining ratio can be further improved. As for the optical semiconductor element provided on the sub-substrate, a light detection element can be used. In this case, the optical module can be used as a light receiving module. Alternatively, for the optical semiconductor element, a light emitting element can be used. In this case, the optical module can be used as a light transmitting module. (4) Embodiments The preferred embodiments of the optical module of the present invention will be described in detail below with reference to the drawings. In the description of the drawings, the same elements are assigned the same reference numerals, and redundant descriptions are omitted. In addition, the size ratio of the drawings is not necessarily the same as that of the explainer. Figure 1 is a side cross-sectional view showing the structure of one embodiment of the optical module. The structure of the optical module of this embodiment will be briefly described using this first figure. This optical module is an optical module for optical transmission or optical reception that transmits optical signals side by side by optically connecting N (N is a natural number) optical fibers with N optical semiconductor elements. In the embodiment described below, N = 4. Further, Fig. 1 shows a cross-sectional view of a plane including an optical module and an optical axis of each of the optical semiconductor elements in one of the four groups. In the first figure, 9-200428057, the left-right direction is the light transmission direction along the optical axis of the optical fiber. The optical module is provided with a circuit substrate 41, a submount 1, an optical fiber fixing member 2, and a covered optical fiber array 31. The circuit substrate 41 is a mounting substrate for assembling the daughter substrate 1. In addition, wiring and electronic circuits required for signal processing are assembled on the circuit board 41. In Fig. 1, a pre-amplifier 43 for amplifying an electric signal and outputting the signal is mounted on a circuit board 41. The sub substrate 1 is a substrate on which an optical semiconductor element is provided. The sub substrate 1 is mounted on a circuit substrate 41. The surface opposite to the circuit substrate 41 of the sub-substrate 1 is an optical element installation surface (first surface) 16 on which the optical semiconductor element is disposed. As the substrate of the sub substrate 1, for example, a silicon substrate can be used. A photodiode array 11 is provided on the light element installation surface 16. The photodiode array 11 is used as an array of four photodiodes (photodetection elements) 12 arranged at a certain distance from each other. These photodiodes 12 are arranged in a direction perpendicular to the optical axis of the optical fiber 3 described later (the direction perpendicular to the paper surface in FIG. 1) as the alignment direction. In addition, the pre-amplifier 43 on the circuit substrate 41, the photodiode array 11 of the sub-substrate 1, and the circuit substrate 41, and the electrodes and wiring provided on the sub-substrate 1 are respectively bonded by a chip junction method or a wire bond. And make electrical connections. The optical fiber fixing member 2 is provided so that the sub-substrate 1 is on the side opposite to the circuit substrate 41. In addition, the surface facing the optical element installation surface 16 of the sub-substrate 1 of the optical fiber fixing member 2 becomes the optical fiber fixing surface (second surface) 26 for fixing the optical fiber. The optical fiber fixing member 2 may be, for example, integrally molded from a resin. On the optical fiber fixing surface 26, there are four fixing grooves for positioning and fixing the optical fiber-10-200428057, which are formed as four V grooves 21 parallel to each other. A coated optical fiber array 31 having four optical fibers aligned at a pitch is provided for these V-grooves. The covering fiber array 31 has a predetermined length of coating removed at the front end portion thereof, and four optical fibers 3 are exposed. Then, these exposed optical fibers are positioned and fixed in the corresponding V-grooves 21 respectively. These V-grooves 21 and the optical fibers 3 fixed in the V-grooves 21 are arranged in a direction perpendicular to the optical axis of the fibers 3, and are arranged at the same pitch corresponding to the photodiodes. In addition, the optical fiber fixing member 2 is provided with the optical fiber fixing portion which is located above the sub-substrate 1 and is provided with the V groove 21, as viewed from the sub-substrate 1 and the optical fiber fixing portion 2a, it extends toward the coated optical fiber array 31; Array receiving portion 2b protruding in the direction. Further, the optical fiber fixing surface 26 is provided with a concave mirror 22 on an individual axis of the optical fiber 3 at a position opposed to its end surface. This concave mirror is provided for each of the four V-grooves 21 and the optical fiber 3. The concave mirror is arranged on the optical axis facing the corresponding photodiode 12 when viewed from the sub-substrate 1. The concave mirror 22 transforms the light path of the light emitted from the end face of the optical fiber 3 vertically downward by about 90 °, while guiding the light as parallel light and condensing the light toward the photodiode 12. A spherical lens 14 is provided between the concave mirror 22 and the photodiode 12, and is positioned so that its optical axis coincides with the optical axis of the photodiode 12. The spherical lens 14 can condense the light emitted from the optical fiber 3 and changing the optical path by the concave mirror 22 toward the corresponding photodiode 12. In this embodiment, by using these concave mirrors and spherical lenses 14, an optical guiding system between the optical fiber 3 and the optical diode 12 can be constructed. The positioning system of the spherical lens 14 can be implemented, for example, by fixing it to a lens mounting stage formed using a resist or the like in the semiconductor process similar to the light -1 1 to 200428057 polar array 11. The circuit board 41, the sub-board 1, the optical fiber fixing member 2, and the like described above are housed in a frame 45 composed of a frame body portion 44a and a frame cover portion 44b located above the frame body portion 44a. On the bottom 45a of the housing body portion 44a, a surface opposite to the surface on which the circuit board 41 and the sub-board 1 are assembled is provided to face the bottom 45a. Among the side portions of the frame 45, an opening 47 is provided on the optical axis of the optical fiber 3 on the side portion 45b of the optical fiber fixing portion 2a that faces the array accommodating portion 2b. The opening 47 passes through the covering optical fiber array 31 , Filled with solder 48. This solder 48 can fix the covered optical fiber array 31 to the frame 45, and can plug the opening 47 to maintain the airtightness of the frame 45. Therefore, in a case where the coated optical fiber array 31 is fixed with the solder 48, it is preferable to use a metal made of, for example, a metalized fiber in the coating of the coated optical fiber array 31. Alternatively, the fixing to the frame 45 of the coated optical fiber array 31 may be performed using a resin or the like. An output terminal 42 is inserted in a side portion 4 5 c which is opposite to the side portion 4 5 b of the housing 45. This output terminal 42 guides the electric signal amplified by the preamplifier 43 from the photodiode 12 to the outside of the housing. FIG. 2 is a perspective view of the daughter board 1 as viewed from the optical fiber fixing member 2. The configuration of the sub substrate 1 will be described in detail using this second figure. On the light element mounting surface 16 of the sub-substrate 1, two guide grooves 10 are formed as first positioning portions and extend parallel to each other. Guide groove 10 is used for positioning optical fiber 3 and light-12- 200428057 diode 12 by passive alignment. The direction in which the guide grooves ι0 are formed is a direction perpendicular to the alignment direction of the photodiodes 12. The guide groove 10 is provided at a predetermined position corresponding to the second positioning portion having the optical fiber fixing member 2. In addition, the cross-sectional shape taken along the vertical plane in the longitudinal direction of the guide groove 10 is such that the width gradually becomes a narrow taper shape from the optical element installation surface 16 toward the inside of the sub-substrate 1. A positioning mark 13 is formed on the optical element installation surface 16. The positioning mark 1 3 is used as a reference when the photodiode array 11 is positioned and fixed to the sub-substrates 丨. The positioning mark 1 3 is used for positioning the two guide grooves 10, and is preferably formed by using the same mask process as the guide groove 10. A photodiode array 11 is provided at a position on the upstream side with respect to the positioning mark 13 as the optical transmission direction of the optical fiber 3. The sub-substrate 1 fixes the photodiode array 1 1 using, for example, flip-chip bonding. In addition, the guide groove 10 serving as the first positioning portion positions the photodiode array 11.

FIG. 3 is a perspective view of the optical fiber fixing member 2 viewed from the sub-substrate 1 side. The configuration of the optical fiber fixing member 2 will be described in detail using this third figure. On the optical fiber fixing surface 26 of the optical fiber fixing member 2, two guide rails 20 are formed as second positioning portions extending in parallel with each other. The guide rail 20 is fitted with the guide groove 10 so that the optical fiber 3 and the light diode 12 are positioned in a passive alignment manner. The cross-sectional shape of the guide rail 20 taken along the vertical plane in the longitudinal direction is also the same as the guide groove 10, which gradually becomes a narrow push-out shape from the optical fiber fixing surface 26 to the inner side of the sub substrate 1. The formation direction of the guide rail 20 is parallel to the formation direction of the V-groove 21. The optical fiber fixing surface 26 is formed in a concave shape along the light transmission direction when viewed from the -13-200428057 arrangement direction of the optical fibers 3 perpendicular to the light transmission direction. The concave portion is a V-groove forming portion 26a for forming the V-groove 21 for fixing the optical fiber 3. With this configuration, the distance between the optical fiber 3 and the concave mirror 22 provided on the optical fiber fixing surface 26 and the light diode 12 provided on the optical element installation surface 16 can be set appropriately. In this embodiment, an upstream portion in the light transmission direction of the V-groove forming portion 26a becomes the array accommodating portion 2b, and a downstream portion becomes the optical fiber fixing portion 2a. As described in FIG. 1, four V-grooves 21 are formed along the light transmission direction, and four concave mirrors 22 are provided on the downstream side thereof. Seen from the alignment direction of the optical fibers 3, both sides of the V-groove forming portion 26a become individual rail forming portions 26b. The two guide rails 20 are provided one on each of the rail forming portions 26b on both sides, and four V grooves 21 formed on the V groove forming portions 26a are pinched. These guide rails 20 as the second positioning portion are used to position the V-groove 21 and the optical fiber 3 fixed to the V-groove 21. The width of the optical fiber fixing surface 26 formed by the V-groove forming portion 26a and the guide rail forming portion 26b in the arrangement direction of the optical fibers 3 is substantially the same as the width of the sub-board 1. When viewed from the direction in which the optical fibers 3 are aligned, individual guide portions 27 are provided on both sides of the optical fiber fixing surface 26 that becomes the outside of the guide rail forming portion 26b. The guide portion 27 projects from the optical fiber fixing surface 26 toward the side where the sub-substrate 1 is arranged. When the optical fiber fixing member 2 is positioned and fixed to the sub-substrate 1, it is used to guide the guide rail 20 and the guide groove 10. Chimeric part. The protruding height of the guide portion 27 is set smaller than the height of the sub substrate 1. Fig. 4 is a perspective view showing a state in which the optical fiber fixing member 2 shown in Fig. 3 is fixed with an optical fiber array 31 and an optical fiber 3 covered with a 1-200428057. As shown in FIG. 4, the optical fiber 3 is fixed to each of the four V grooves 21. This fixing is performed after the optical fiber 3 is inserted into the V-groove 21 and then fixed with an adhesive. When fixing, a glass plate or the like can be used as the optical fiber pressing tool. Fig. 5 is a front cross-sectional view taken along the line I-I of the optical module shown in Fig. 1. The optical fiber fixing member 2 is provided such that the guide portion 27 of the optical fiber fixing member 2 holds the sub-board 1 from both sides, and at the same time, guides 26 b of the optical fiber fixing surface 26 of the optical fiber fixing member 2 and the optical element installation surface 16 of the sub-board 1 Pick up. At this time, as shown in Fig. 5, the guide groove 10 formed in the sub-substrate 1 is fitted into the guide rail 20 formed in the optical fiber fixing member 2. Therefore, the photodiode 12 positioned on the guide groove 10 and the optical fiber 3 positioned on the guide rail 20 can be positioned in a passive alignment manner. In addition, the optical fiber fixing member 2 and the circuit board 41 below the sub board 1 are fixed using an adhesive. FIG. 5 shows an adhesive 46 filled between the lower surface of the guide portion 27 of the optical fiber fixing member 2 and the upper surface of the circuit board 41. As shown in FIG. Next, the combined process of the optical module will be described using FIG. 1. First, the circuit board 41 is mounted on the frame body portion 44a. The sub-board 1 and the preamplifier 43 are mounted on the circuit board 41. These mountings can be performed using a resin sheet bonding method, a gold wire or an aluminum wire bonding wire, or the like. On the other hand, the optical fiber 3 is fixed to the optical fiber fixing member 2 in a separate process other than the installation process of the sub substrate 1. Then, the guide rail 20 is fitted into the guide groove 10, and the optical fiber fixing member 2 to which the optical fiber 3 is fixed is positioned and fixed to the sub substrate 1. In this state, the adhesive 46 is filled in a predetermined space 15-200428057, and the optical fiber fixing member 2 is adhered and fixed to the circuit substrate 41. Finally, after covering the coated fiber array 31 through the opening 47, the frame body cover portion 44b is closed and fixed to the frame body portion 44a, thereby completing the optical module. This closed fixing can be performed by adhesively fixing using resin. The effect of the light module of this embodiment will be described. In this optical module, since the guide groove 10 of the sub substrate 1 is fitted with the guide rail 20 of the optical fiber fixing member 2, the optical fiber 3 and the optical diode 12 can be positioned. Therefore, in this optical module, passive positioning can be achieved. The guide groove 10 is used as the first positioning portion, and the guide rail 20 is used as the second positioning portion. Therefore, the optical fiber 3 and the photodiode 12 can be positioned with high accuracy. Alternatively, the first positioning portion formed on the sub-substrate 1 may be used as a guide groove, and the second positioning portion formed on the optical fiber fixing member 2 may be used as a guide rail.

In addition, since the optical fiber fixing surface 26 is arranged to be opposite to the optical element installation surface 16, the process of positioning and fixing the optical fiber fixing member 2 to which the optical fiber 3 is fixed to the sub substrate 1 can be performed by placing the sub substrate on the circuit substrate. The process of chip bonding, wire bonding, etc. is performed later. Therefore, there is no obstacle in processing or automation in the process of chip bonding, bonding wire bonding, etc. of the sub-substrate on the circuit substrate, and thus it is possible to realize mass production and low-cost optical modules. In addition, since the first surface of the optical fiber pair substrate is arranged in parallel, the height of the module can be reduced. Furthermore, a concave mirror 22 is provided as a light-guiding optical system between the optical fiber 3 and the light diode 12. Therefore, light emitted from any one of the optical fiber and the optical semiconductor element is collected and guided to the other side, so that a high light -16-200428057 coupling ratio can be achieved. In addition, in this embodiment, the concave mirror 22 can make the light from the optical fiber 3 parallel, so that the optical path of the light from the optical fiber 3 from the concave mirror 22 to the spherical lens 14 can be advanced as parallel light. The error of the optical module is reduced. For example, according to calculations using optical simulation, when the positional relationship between the concave mirror 22 and the photodiode 12 is shifted to about ± 40 // m, the result of light combination can also be obtained. The concave mirror 22 is not limited to making the reflected light into parallel light. In addition, according to the optical module, a plurality of optical fibers 3 and a plurality of optical diodes 12 can be set separately, so that a plurality of optical signals can be transmitted in parallel. Therefore, an optical module capable of transmitting at a higher speed and a larger capacity can be realized.

A spherical lens 14 for condensing is provided between the photodiode 12 and the concave mirror 22. Therefore, a high photo-combination ratio can be achieved. However, in the case where a sufficient light combining ratio can be obtained with only the concave mirror 22, the spherical lens 14 may not be provided. For example, a case where a single-mode fiber having a core diameter of 10 m is used as the optical fiber 3, or a case where the light detection diameter of the photodiode 12 is sufficiently large is used. The positioning of the spherical lens 14 can be performed, for example, by fixing the lens on a pedestal for mounting a lens using a resist or the like in a semiconductor process similar to that of the photodiode array 11. Therefore, the spherical lens 14 can be positioned with an accuracy of less than 1 to 2 // m. In addition, the positioning mark 13 and the guide groove 10 are formed by the same mask process, and the positioning mark 13 can be positioned to the guide groove 10 with a precision of 1 to 2 / z m or less. Therefore, in this case, the photodiode array 11 and the 2004-17057 guide groove 10 can be positioned with respect to each other with high accuracy. When the photodiode array Π is made of the same material as the sub-substrate and uses the same semiconductor process, a single wafer can be formed with the guide groove 10. In this case, the photodiode array 11 and the guide groove 10 can be positioned with respect to each other with high accuracy. In this case, it is not necessary to form the positioning marks 1 to 3. In addition, when the fixing system of the photodiode array 11. and the sub-substrate 1 is assembled using flip-chip bonding, it can be positioned with an accuracy of ± 5 / ζ m or less. In the case where the optical fiber fixing member 2 is integrally formed of resin, the distance between the V-groove 21 and the concave mirror 22, the relative positional relationship between the V-groove 21 and the concave mirror 22, and the relative positional relationship between the guide rail 20 and the V-groove 21, It is made with high accuracy with an accuracy of ± 5 / zm or less. The optical fiber fixing member 2 can be integrally molded using metal injection molding (MIM). In the case of this molding, it can be manufactured with the same high precision as in the case of integral molding with resin. Further, in the optical fiber fixing member 2, an adhesive having refractive index integration characteristics may be filled between the optical fiber 3 and the concave mirror 22. Therefore, reflected light from the front end of the optical fiber 3 can be suppressed. The guide rail 20 is formed substantially parallel to the V groove 21. Therefore, the guide rail 20 and the V groove 21 can be easily positioned and formed. Furthermore, the guide rails 20 are formed one by one on the rail forming portions 26b located on both sides of the V-groove 21, so that the sub-substrate 1 and the optical fiber fixing member 2 can be positioned with high accuracy. The cross-sectional shape of the guide groove 10 and the guide rail 20 taken in a vertical plane toward the long side direction is made into a push shape. Therefore, the fitting of the guide groove 10 and the guide rail 20 200428057 can be facilitated. Further, since the guide portion 27 is provided on the optical fiber fixing member 2, the fitting of the guide groove 10 and the guide rail 20 can be easily performed with only easy contact. However, the optical module in which the guide rail and the guide groove are fitted to position the optical fiber and the optical semiconductor element is also disclosed in Japanese Patent Application Laid-Open No. 7-77634 and Japanese Patent Application Laid-Open No. 7- 1 5 1 940. Japanese Unexamined Patent Publication No. 7-77634 describes that the guide rail formed on the substrate for fixing the optical fiber is fitted with the guide groove formed directly on the optical semiconductor element, so that the optical fiber and the optical semiconductor element can be passively aligned. Positioning light module. However, in this optical module, the optical fiber and the optical semiconductor element are arranged along the same optical axis. Therefore, a mounting portion for mounting an optical semiconductor element on the substrate along the optical axis must be added to the fixed portion of the optical fiber. Therefore, there is a problem that the optical module cannot be miniaturized. In contrast, the optical module of the present invention is provided with a concave mirror 22 that converts the light path of the light emitted from the optical fiber 3, so that the light from the optical fiber 3 can be incident on a position opposite to the optical fiber fixing surface 26 The structure of the light diode 12. Therefore, it is not necessary to set the setting part of the photodiode 12. Therefore, the optical module can be miniaturized. In addition, Japanese Unexamined Patent Publication No. 7-195940 describes an optical module in which a substrate for positioning is provided in addition to the optical fiber fixing member and the sub-substrate. However, in this optical module, the positioning section not only Only the optical fiber fixing member 2 and the sub substrate must be formed on the substrate. As a result, the formation process of the positioning unit, and the manufacturing process of the entire optical module is complicated. In addition, since the fitting portions of the positioning portions are independent of each other and there are two locations (two locations between the optical fiber fixing member-substrate and the sub-substrate substrate), there is a problem that the errors of the positioning portions are enlarged. In contrast, the optical module of the present invention is provided with positioning portions 10 and 20 only for the sub-substrate 1 and the optical fiber fixing member 2, and positioning can be performed when these are directly fitted. Therefore, the optical module not only simplifies the manufacturing process, but also enables positioning with high accuracy. In addition, the passive alignment type optical module may be considered, for example, the structure shown in FIG. 6. In the optical module of FIG. 6, the positioning of the optical fiber 82 and the optical semiconductor element 84 is performed by using a V-groove and a positioning mark formed on the substrate 81 using the same mask process. A plane mirror 85 is provided on the substrate 81 to guide light between the optical fiber 82 and the optical semiconductor element 84.

However, in this optical module, the optical fiber 82 enters below the optical semiconductor element 84. Therefore, after the optical fiber 82 is adhesively fixed to the V-groove, the optical semiconductor element 84 performs chip-on-chip assembly using the positioning marks as a guide. Therefore, it may cause obstacles in processing or automation in the process of flip-chip assembly of the optical semiconductor element 84. As a result, the optical module has problems such as mass production and cost reduction. In contrast, in the optical module of FIG. 1, after the sub-substrate 1 is bonded to the circuit substrate by chip bonding, wire bonding, etc., the optical fiber fixing member 2 to which the optical fiber 3 is fixed can be positioned on the sub-substrate 1. fixed. Therefore, this optical module can achieve mass production and cost reduction. Furthermore, in the optical module of FIG. 6, the inside of the optical semiconductor element 84 (the surface on the opposite side from the light detection element -20-200428057) becomes floating. Therefore, there is a problem that heat radiation from the optical semiconductor element 84 cannot be performed efficiently. This problem, especially when using VCSELs (lasers emitted from the surface of the vertical chamber) with high heat generation, is the main reason for the unstable operation of the optical module. In contrast, in the light module of Fig. 1, the photodiodes 12 and 2 are arranged on the sub-substrate 1, so that the inside thereof does not become floating. Therefore, the present optical module can efficiently perform heat radiation from the photodiode 12.

In addition, in the optical modules shown in Figs. 6 and 7, there is a problem that the light combining ratio is low because a condensing optical system such as a concave mirror is not used. That is, in consideration of the high-speed operation of about 2.5 Gbps, the optical semiconductor elements 84 and 94 are generally those having a detection diameter of 40 to 80 #m. On the other hand, the distance along the optical axis from the optical fibers 82, 92 to the optical semiconductor elements 84, 94 must be greater than the diameter (125 μm) of the cladding of the optical fiber in FIG. 6 and must be in FIG. 7 Above the loop height (approximately 100 / Z m) of the bonding wire used for bonding. As a result, the spot welding diameter of the optical semiconductor elements 84 and 94 was 117.5 // m in the case of a core diameter of 62.5 / zm and the number of openings of 0.275, and 92 / zm in the case of a core diameter of 50 μm. Of the elements 84 and 94, the total amount of light cannot be detected. In particular, when a multimode fiber having a large core diameter and a large number of openings is used, the optical coupling ratio is further reduced. On the other hand, in the optical module of FIG. 1, the light from the optical fiber 3 is guided to the photodiode 12 by the concave mirror 22 to collect light, so that a high light combining ratio can be achieved. An example of the optical design of the optical module of the present invention will be described. Here, we want to use a multimode fiber with a core diameter of 62.5 / zm and a number of openings of 0.275 as the optical fiber 3-21- 200428057, and use a 2.5 Gbps high-speed light detection diameter of 80 μm as the photodiode 12 Happening. The arrangement pitch of the photodiodes 12 in the photodiode array 11 is 2 5 0 // m. In this case, in order to prevent the so-called cross-line interference of light from one optical fiber 3 being incident on the light detection portions of two or more photodiodes 12, considering the edge portion, it is necessary to suppress the spread of the light beam to 200 # m or less. Therefore, the distance between the optical fiber 3 and the concave mirror 22 is set to 250 / z m as an upper limit.

On the other hand, even if the distance between the concave mirror 22 and the photodiode 12 is not provided with a spherical lens 14, it is necessary to take into consideration the space for bonding wires and make it 25 0 // m or more. In addition, the distance from the reflection center of the concave mirror 22 to the optical fiber 3 must also be considered. Therefore, the distance between the concave mirror 22 and the photodiode 12 must be made to be 312.5 β m or more. In the case where a glass plate or the like is used as an optical fiber fixture, its thickness must be considered, so the lower limit of the interval becomes larger than 312.5 / zm.

From the above description, in the optical module of the present invention, the distance between the concave mirror 22 and the light diode 12 becomes larger than the distance between the optical fiber 3 and the concave mirror 22, and thus becomes an enlarged optical system. Even when the former interval is set to 25 0 / zm as the upper limit and 312.5 # m as the lower limit to the latter, the magnification becomes 1.25 and the image of a core with a diameter of 62 · 5 / zm becomes Image of diameter 78 on photodiode 12. At this time, although the light detection diameter of the photodiode 12 is 8 0 // m, it is difficult to achieve a 10% light-combination rate when considering the tolerances when manufacturing the components 1,2 and their combinations. . Therefore, in this optical module, a light condensing optical system provided with a concave mirror 22 or the like is used to condense light from the optical fiber 3 and guide the light to the photodiodes 12 -22-200428057. Therefore, in this optical module, 100% light combining ratio can be realized. In the optical modules shown in FIGS. 1 to 5, although the number N of the number of optical fibers 3 and the number of optical diodes 12 is 4, the number N may be appropriately determined. set up. When N is set to 2 or more, as described above, a plurality of optical signals can be transmitted in parallel, so that higher-speed and large-capacity transmission is possible. In addition, when N is set to 1, the same effects as the optical modules shown in Figs. 1 to 5 can be achieved in the positioning of the optical fiber 3 and the photodiode 12. For the optical semiconductor element, a light detection element other than the photodiode 12 may be used, or a light emitting element such as a VCSEL may be used. When a light-emitting element is used, the concave mirror 22 guides the light emitted from the light-emitting element to the optical fiber 3, and the spherical lens 14 focuses the light emitted from the light-emitting element. Possibility of industrial use As a light module suitable for mass production and low cost. That is, in the optical module of the present invention, the optical fiber and the optical semiconductor element can be positioned by fitting the first positioning portion and the second positioning portion. Therefore, the optical fiber and the optical semiconductor element can be positioned in a passive alignment manner. In addition, since the guide rail and the guide groove are used as the positioning portion, the optical fiber and the optical semiconductor element can be positioned with high accuracy. In addition, the process of positioning and fixing the optical fiber fixing member to which the optical fiber is fixed on the sub substrate can be placed later in the process of bonding the sub substrate on the circuit substrate, and the process of-23-2 (00428057 wire bonding). Implementation. Therefore, optical modules suitable for mass production and low cost can be realized. Moreover, the first surface of the optical fiber pair sub-substrate is arranged in parallel, so that the module height can be reduced. Furthermore, a concave mirror is provided to As an optical system for guiding light between an optical fiber and an optical semiconductor element. Therefore, light emitted from one of the optical fiber and the optical semiconductor element is focused and guided to the other side, so that a high optical coupling ratio can be achieved. V) Simple illustration

Fig. 1 is a side sectional view showing the structure of one embodiment of an optical module, and Fig. 2 is a perspective view of a sub-substrate including the optical module shown in Fig. 1. Fig. 3 is provided with Fig. 1. A perspective view of the optical fiber fixing member of the optical module; FIG. 4 is a perspective view showing a state where the optical fiber is fixed on the optical fiber fixing member shown in FIG. 3;

Fig. 5 is a front cross-sectional view taken along line I-I of the optical module shown in Fig. 1. Fig. 6 is a side cross-sectional view showing a configuration example of an optical module using a passive alignment method. Fig. 7 It is a side cross-sectional view showing a configuration example of a light module using a passive alignment method of the prior art. Component symbol description 1 Sub-substrate 2 Optical fiber fixing member -24- Fiber fixing portion Array receiving portion Fiber guide groove Light diode array Light diode positioning mark Spherical lens Light element installation surface guide V groove Concave mirror Fiber fixing surface V groove forming portion Guide rail formation Part guide part covering fiber array circuit board output terminal preamp frame body body frame cover body bottom-25- 45b side 45c side 46 adhesive 47 opening 48 solder 81 substrate 82 optical fiber 84 optical semiconductor element 85 flat mirror

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Claims (1)

200428057 Scope of patent application: 1. An optical module, comprising: a sub-substrate having an optical semiconductor element provided on a predetermined first surface and a first positioning formed on the first surface An optical fiber fixing member having a fixing groove formed on the second surface and positioning and fixing the optical fiber; The light emitted by either side is guided to the concave mirror used by the other side, and the second positioning portion formed on the second surface; the optical fiber fixed to the fixed groove; the first positioning portion and the second positioning portion are one of the guide rails, The other side is formed by a guide groove fitted to the guide rail, and the sub-substrate and the optical fiber fixing member are positioned and fixed by fitting the first positioning portion and the second positioning portion. 2 · The optical module according to item 1 of the patent application scope, which includes: a sub-substrate having N (N is an integer of 2 or more) optical semiconductor elements; and N fixed grooves parallel to each other, and The optical fiber fixing members of the N concave mirrors provided in the n fixing grooves; and the n optical fibers respectively fixed in the N fixing grooves. 3. The optical module according to item 1 of the patent application scope, wherein the optical semiconductor element is made of the same material as the sub-substrate and uses the same semiconductor process, and thus can be formed into a single block with the first positioning portion. 200428057 4 · If the optical module of the first patent application scope 'wherein the sub-substrate has a positioning mark formed by the same mask process as the first positioning portion', the optical semiconductor element can use the positioning mark as a reference 'and Set to position the sub-substrate. 5 · The optical module of item 1 of the patent application range, wherein the optical fiber fixing member is made of resin integral molding. 6. The light module according to item 1 of the scope of patent application, wherein the second positioning portion is formed substantially parallel to the fixing groove. 7 · The light module according to item 1 of the scope of patent application, wherein the guide rail is a push-out shape with a cross-sectional shape taken along a vertical plane toward the long side direction. 8 · The optical module according to item 1 of the patent application scope, which includes a lens disposed between the optical semiconductor element and the concave mirror and condensing light emitted from one of the optical fiber and the optical semiconductor element toward the other. . 9. The optical module according to item 1 of the scope of patent application, wherein the optical semiconductor element is a light detection element. 1 0. The optical module according to item 1 of the patent application scope, wherein the optical semiconductor element is a light emitting element. -28-